KR20130095196A - Dry cellulose gel and process for producing same - Google Patents

Abstract

After mixing 15-25 wt% of cellulose powder while spraying misty water in a kneader containing water, the step of kneading water and cellulose powder under vacuum to obtain a cellulose kneaded product and the cellulose kneaded product with an electron beam The method of manufacturing the dried cellulose gel containing the process of irradiating and obtaining a crosslinked cellulose gel, and the process of drying the said crosslinked cellulose gel and obtaining a dry cellulose gel.

Description

Dry cellulose gel and its manufacturing method {DRY CELLULOSE GEL AND PROCESS FOR PRODUCING SAME}

TECHNICAL FIELD The present invention relates to a dry cellulose gel, and more particularly, to a dry cellulose gel excellent in water absorption and a method for producing the same.

The manufacturing method of the self-crosslinking alkyl cellulose derivative using radiation irradiation is proposed (patent documents 1-2).

The method described in Patent Literature 1 is irradiated with a radiation containing 0.1 kGy in terms of gamma ray to a mixture containing 5 to 2,000 parts by weight of water with respect to 100 parts by weight of the alkyl cellulose derivative and dried. Although the alkyl cellulose derivative alone is decomposed by irradiation, in the presence of water, hydroxy radicals are generated to generate a self-crosslinking reaction.

The method described in Patent Literature 2 is an improvement of the method described in Patent Literature 1 according to the present inventors, and in order to eliminate the complexity of the drying step and the molding step after self-crosslinking by radiation, Then, the method of drying is proposed. In the method described in Patent Document 2, the cellulose powder and water are kneaded with an extruder, and in particular, γ-rays, X-rays, and electron beams from cobalt 60 are irradiated and crosslinked to form a cellulose gel, and then cut, granulated and dried. Let's do it. However, as a result of repeating the experiments by the present inventors, it was found that the absorptivity of the cellulose gel obtained was not uniform and that it could not be mass produced.

Japanese Laid-Open Patent Publication 2001-2703 Japanese Unexamined Patent Publication No. 2009-179706

In the dry cellulose gel obtained by the method of patent documents 1 and 2, there exists a problem that water absorption is low, a dispersion | variation arises in water absorption, and it cannot mass-produce. Accordingly, an object of the present invention is to provide a dry cellulose gel excellent in water absorption and a manufacturing method for mass production of the dry cellulose gel.

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve a subject, the present inventors discovered that the cause of the fall and the deviation of an absorbency were the nonuniformity of the alkylcellulose derivative-water mixture at the time of irradiation, and the presence of a bubble, and completed this invention.

That is, according to the present invention, 15-25 wt% of cellulose powder is added to the kneader into which water is added while spraying misty water, followed by kneading water and cellulose powder under vacuum to obtain a pasty cellulose kneaded product. The manufacturing method of the dried cellulose gel is provided including the process, the process of irradiating an electron beam to the said cellulose kneaded material, and the process of drying the said crosslinked cellulose gel, and obtaining a dry cellulose gel.

In the present invention, by kneading water and cellulose powder under vacuum, bubbles are taken out from the kneaded paste-like cellulose kneaded material, and the unevenness of the degree of crosslinking caused by the presence of bubbles during electron beam irradiation can be eliminated. have.

When water is first introduced into the kneader and the cellulose powder is introduced, the cellulose powder is scattered, and not only a predetermined amount of cellulose powder can be introduced, but also the cellulose powder is sucked under vacuum when kneading under vacuum. In order to enable the kneading under a vacuum, the present invention can spray misty water onto the cellulose powder at the time of introduction of the cellulose powder into the kneader, thereby preventing the cellulose powder from scattering up, and the wettability of the water and the cellulose powder. Can improve.

It is preferable that it is carboxyalkyl cellulose, and it is especially preferable that it is carboxymethyl cellulose sodium.

In addition, since the carboxyalkyl cellulose reacts with chlorine, the water to be introduced directly into the kneader and the water to be sprayed are preferably water that does not contain chlorine or alcohol, and more preferably desalted and degassed water.

Water and powdered cellulose at the time of vacuum kneading are adjusted so that the powdered cellulose has a content of 15 to 25 wt%. When there is too much content of powdered cellulose, crosslinking reaction by electron beam irradiation will not advance and the decomposition reaction of cellulose will give priority. On the contrary, when there is too little content of powdered cellulose, in order to produce the crosslinking reaction by electron beam irradiation, a large amount of electron beam irradiation will be needed and cost will become high.

In this invention, it can be bridge | crosslinked by irradiation of a very short time by using an electron beam for a cellulose kneaded material. Although the irradiation amount of the said electron beam changes with content of powder cellulose, it is preferable that it is 9-16 kGy in the range of 15-25 wt% of powder cellulose. If the amount of electron beam irradiation is large, the net of a crosslinked structure will become small, and if the amount of electron beam irradiation is small, the net of a crosslinked structure will become large. If it is in the said range, the water absorption of a dry cellulose gel can be raised.

It is preferable that the manufacturing method of this invention further includes the process of shape | molding the said cellulose kneaded material under vacuum. By molding under vacuum, it is possible to avoid generating excess bubbles in the cellulose kneaded product containing water.

According to the manufacturing method of the said invention, the dry cellulose gel whose absorption magnification calculated | required by dividing the gel which absorbed for 24 hours by the initial weight before absorption is 150 or more is obtained.

Moreover, according to this invention, it is an apparatus for implementing the manufacturing method of the dry cellulose gel of this invention, The kneading | mixing kiln provided with a stirring blade, the water pipe formed along the inner peripheral part, and the water spray formed in the said water pipe at equal intervals. A vacuum kneading apparatus including a lid having a portion and a vacuum suction unit; An electron beam irradiation apparatus including a belt conveyor for conveying the cellulose kneaded product taken out of the vacuum kneading apparatus, an electron beam irradiation unit, and an electron beam source; And a breathable belt conveyor for conveying the cellulose gel taken out of the electron beam irradiation device, and a drying device including a circulation fan for blowing hot air from above the belt conveyor.

By using the manufacturing method of this invention and the manufacturing apparatus for implementing the said manufacturing method, the dispersion | variation in water absorption can be suppressed and mass production of the dry cellulose gel excellent in water absorption is attained.

1 is a schematic flow chart showing a manufacturing process of the present invention.
It is explanatory drawing which shows the outline of the whole manufacturing apparatus used by this invention.
3: (A) is a schematic front view which shows the vacuum kneading apparatus used by this invention, FIG. 3 (B) is a schematic side view, and FIG. 3 (C) is sectional drawing in the A line of FIG.
It is a schematic sectional drawing which shows the electron beam irradiation apparatus used by this invention.
4B is a schematic plan view.
It is a schematic sectional drawing which shows the extrusion apparatus used by this invention.
It is a schematic sectional drawing which shows the drying apparatus used by this invention.
7A is a bar graph showing the measurement results of the absorption magnification according to Example 1. FIG.
7B is a bar graph showing the measurement results of the absorption magnification according to Example 1. FIG.
7C is a bar graph showing the results of measurement of absorption magnification according to Example 1. FIG.

The manufacturing method and apparatus of this invention are demonstrated, referring drawings.

First, the manufacturing apparatus of this invention is demonstrated, referring FIGS.

As shown in FIG. 2, the manufacturing apparatus of this invention is equipped with the vacuum kneading apparatus 10, the electron beam irradiation apparatus 100, and the drying apparatus 200. As shown in FIG.

As shown in FIG. 3, the vacuum kneading apparatus 10 includes a kneading kiln 20, a lid 30, a lifting cylinder 40 for raising and lowering the lid 30, a hydraulic / vacuum unit 50, and the like. And a kneading motor 60. The lid 30 is equally spaced between the stirring blade 31, the raw material inlet 32, the oil and water pipe 34 formed on the inner periphery of the lid above the raw material inlet 32, and the oil and water pipe 34. It is provided with the water spray part 33 formed. In use, the lid 30 descends to the position of the kneading kiln 20 by the lifting cylinder 40. After joining the lid 30 and the kneading | mixing kiln 20 in the sealed state, the inside of the kneading | mixing kiln 20 is vacuum-sucked by the hydraulic and vacuum unit 50, and the stirring blade 31 is kneaded the motor 60 for kneading | mixing. Drive by.

As shown in FIG. 4, the electron beam irradiation apparatus 100 includes a belt conveyor 110 for conveying the cellulose kneaded product prepared by the vacuum kneading apparatus 10, an electron beam irradiation unit 120 for irradiating an electron beam to the cellulose kneaded material, and And an electron beam source 130. The electron beam irradiation part 120 and the electron beam source 130 are accommodated in the shielding enclosure 140 for preventing an electron beam from leaking outside. In the shield enclosure 140, the belt conveyor 110 is arrange | positioned so that it may become length enough to give a desired amount of electron beam irradiation. For example, the belt conveyor 110 may be a straight path, a bending path, a U-turn path, or a multi-stage three-dimensional path.

The manufacturing apparatus of this invention may be equipped with the extrusion apparatus 150 which shape | molds the crosslinked cellulose gel bridge | crosslinked by the electron beam irradiation apparatus 100 to the shape which is easy to dry process. As shown in FIG. 5, the extrusion device 150 includes a hopper 152 accommodating the crosslinked cellulose gel, a slicer 154 formed under the hopper 152 to cut the crosslinked cellulose gel, and a cut crosslinking. An extruded portion 156 and an outlet 158 are formed to form and extrude a cellulose gel into a spherical shape. The extrusion part 156 is equipped with the cylindrical main body 156a and the extrusion screw 156b currently rotatably formed in the cylindrical main body. At the discharge port 158, a plate member 158a having a circular hole for spherically extruding the crosslinked cellulose gel is formed. The delivery pitch P1 of the front half of the extrusion screw 156b becomes about half of the delivery pitch P2 of the rear half, and aims at increasing the extrusion pressure at the front end side. Between the tip part of the screw 156b and the die | dye type | mold 156c, the space part 156d of skirt shape is formed. In the die die 156c, a plurality of forming holes 156e for granulation are formed, and each forming hole 156e is not shown, but is formed in the thickness direction of the forming hole 156e from the rear surface of the screw 156b side. It becomes a taper hole of the shape tapering slightly toward a middle position, and it is a straight hole whose diameter is constant from the intermediate position to the front surface of the die | dye type | mold 156c. The diameter of the shaping hole 156e differs according to the use of a dry gel, and the die | dye type | mold 156c which has a desired diameter is exchangeably mounted in the extrusion apparatus.

As shown in FIG. 6, the drying apparatus 200 blows hot air from the air permeable belt conveyor 210 which receives and conveys the crosslinked cellulose gel shape | molded by the extrusion apparatus 150, and the belt conveyor 210 upper part. A circulation fan 220, an exhaust duct 230, and an outlet 240 for taking out the crosslinked cellulose gel after drying. The breathable belt conveyor 210 may be made of a punching metal or a mesh metal, and may be configured to vent the hot air from the circulation fan 220. The exhaust duct 230 is formed above the circulation fan 220, and removes the exhaust gas containing moisture removed from the crosslinked cellulose from the drying apparatus 200 when hitting hot air against the crosslinked cellulose gel. It is preferable to form a plurality of circulation fans, and to adjust temperature individually according to the degree of drying of a crosslinked cellulose gel.

Next, the manufacturing process of this invention is demonstrated, referring FIG. S1 is a vacuum kneading process of kneading cellulose powder and water under vacuum, and it is preferable to carry out in the vacuum kneading apparatus 10 shown in FIG. 3. S2 is an electron beam irradiation process which irradiates an electron beam to a cellulose kneaded material, and it is preferable to implement in the electron beam irradiation apparatus 100 shown in FIG. S3 is a drying process of drying a crosslinked cellulose gel, and it is preferable to carry out in the drying apparatus 200 shown in FIG.

<S1>

Water is introduced into the kneading kiln 20 of the vacuum kneading apparatus 10 in advance, and then powdered cellulose is introduced from the raw material inlet 32. When the powdered cellulose is introduced into the kneading kiln 20, misty water is sprayed from the water spraying section 33 formed in the lid 30 to suppress the scattering of the powdered cellulose and to wet the powdered cellulose, The wettability with the water in the kneading | mixing kiln 20 is improved.

After introducing water and powdered cellulose into the kneading kiln 20, the lid 30 is lowered, the inside of the kneading kiln 20 is vacuumed by the hydraulic and vacuum unit 50, and the stirring blade 31 is kneaded. It is driven by the motor 60. The vacuum state in the present invention can be realized by applying a pressure in the range of 500 Pa to 0.13 Pa, more preferably in the range of 130 Pa to 1 Pa by a vacuum pump, and the kneading time is preferably 30 to 60 minutes. Preferably it is 40 to 50 minutes.

Subsequently, the cellulose kneaded product kneaded in vacuum is molded into a dimension and shape suitable for electron beam irradiation. Although shaping | molding can also be performed using a vacuum press machine, a vacuum extruder, etc., you may press and knead the kneading | mixing kiln 20 in a vacuum state, and extrude and cut a cellulose kneaded material from the lower extrusion port.

<S2>

The cellulose kneaded product after molding is loaded on the belt conveyor 110, conveyed into the electron beam irradiation apparatus 100, and is irradiated with the electron beam from the electron beam source 130 by the electron beam irradiation unit 120.

<S3>

The cross-linked cellulose gel obtained by electron beam irradiation is conveyed to the hopper 152 of the extrusion device 150 while being loaded on the belt conveyor 110 and put into the hopper 152. The crosslinked cellulose gel injected into the hopper 152 is cut by the slicer 154 under the hopper 152 and is supplied into the main body of the extrusion apparatus 150. The crosslinked cellulose gel supplied to the extrusion unit 156 of the main body of the extrusion device 150 is extruded toward the discharge port 158 by the cylindrical main body 156a by the screw 156b for extrusion, and has a plate shape of the discharge port 158. It is extruded from the circular hole of the member 158a, spherical, and discharged. At this time, the crosslinked cellulose gel is broken by the rotating screw 156b, and is pushed forward of the cylindrical body 156a while being kneaded. Since the delivery pitch P1 of the front half of the screw 156b becomes about half of the delivery pitch P2 of the rear half, the pressing force with respect to the kneaded material of a crosslinked cellulose gel becomes high gradually, and it is die-type by predetermined extrusion force. A crosslinked cellulose gel is extruded from each forming hole 156e of 156c. At the time of this extrusion, the crosslinked cellulose gel is not elongated continuously in a thin and long state due to the water content of the crosslinked cellulose gel, the viscoelastic strength, or the like, and is extruded as a particulate gel.

The spheroidal crosslinked cellulose gel discharged is received by the breathable belt conveyor 210 of the drying apparatus 200 and conveyed into the drying apparatus 200. The spherical crosslinked cellulose gel is exposed to warm air at a predetermined temperature of 60 to 90 ° C. in each drying chamber in the drying apparatus 200 to become a dry crosslinked cellulose gel and taken out from the outlet 240. At this time, since the hot air repeatedly flows from the upper side to the lower side of the breathable belt conveyor 210 and from the lower side to the upper side, the particulate crosslinked cellulose gel is dried to a residual water content of about 10 wt% while moving at a low speed.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1

Using carboxyalkyl cellulose sodium as the cellulose powder, the content was changed to 15 wt% to 30 wt%, the electron beam irradiation amount was changed to 7 kGy to 16 kGy, and the dry crosslinked cellulose gel was prepared using the production apparatus shown in FIG. Prepared. That is, 10.5 L-12.75 L of water was inject | poured into the kneading | mixing kiln, 2.25-4.5 kg of carboxyalkyl cellulose sodium powder were added, spraying with misty water, and the lid of the kneading | mixing kiln was closed by vacuum suction and vacuum kneading for 40 minutes. . Subsequently, the cellulose kneaded material kneaded in vacuum was transferred to an electron beam irradiation device, and a predetermined electron beam was irradiated and crosslinked to obtain a crosslinked cellulose gel. Subsequently, the crosslinked cellulose gel was transferred to an extrusion apparatus, molded into a spherical shape, then conveyed to a drying apparatus and dried to obtain a dry cellulose gel.

<Absorption magnification>

About each sample, the gel absorbed for 24 hours was divided by the initial weight before absorption and the absorption magnification was calculated | required. Table 1 shows manufacturing conditions and measurement results. In addition, the relationship between the powder cellulose content of Table 1 and the electron beam irradiation amount was made into the bar graph according to the kind of powder cellulose to FIG. 7 (a)-(c).

From Fig. 7, although it varies depending on the kind of cellulose powder used as a raw material, as the content of the cellulose powder increases, the irradiation amount of the electron beam decreases, and there is a combination of the content of the cellulose powder and the electron beam irradiation amount which is optimal for achieving a high absorption magnification. It can be seen that.

In Table 1, "2200" represents "carboxymethyl cellulose sodium CMC2200 manufactured by Daicel Finechem Co., Ltd.", "1350" represents "carboxymethyl cellulose sodium CMC1350 manufactured by Daicel Finechem Co., Ltd.", and "350" represents "Nippon Paper. Carboxymethyl cellulose sodium F350HC-4 ", Inc. is shown.

In Table 1, evaluation item "(circle)" has the absorption magnification of 350 times or more, and shows that it is especially suitable for the use where absorption ability is calculated | required, "(circle)" has the absorption magnification of 150-350 times, and uses of a normal dry gel "△" shows the thing which has the absorption magnification of 90-150 times.

<Evaluation of dry gel>

Although the material number 2200 is comparatively good in the gel as it is after irradiation, the absorption power as a dry gel is inferior in three kinds of materials.

Material article number 1350 is softer than gel number 2200 as it is after irradiation. Among the three kinds of materials, variations tend to occur in the absorbent power of the dried gel.

Material part 350 shows the stable high absorption magnification of the gel and the dried gel which are in the state as it is after irradiation.

<Use of Dry Gel>

The dry gel obtained the evaluation of "◎" in Table 1 is especially used for applications where high liquid absorption performance is required, for example, paper diapers, sanitary products, substitutes for the soil used for flood control, and water repellent for desert greening. Etc., it can be used preferably.

Since the dry gel which obtained evaluation of "(triangle | delta)" in Table 1 has flexibility and strength, and since decomposition is slow, it is suitable as a repair material of a plant.

<Swelling degree>

Further, 1 g of the dried cellulose gel of the present invention was immersed in 1600 g of well water for 18 hours, and the mass before and after swelling was measured to calculate the degree of swelling (= mass after immersion / mass before immersion). Table 2 shows the measurement results of the representative example.

Comparative Example 1

Except having performed kneading | mixing in air | atmosphere, it carried out similarly to Example 1, obtained the dry cellulose gel, and measured the absorption ratio and swelling degree. The results are shown in Tables 3 and 4. Although evaluation of an absorption magnification is "(triangle | delta)", water retention is insufficient and it may decompose | disassemble overnight under high temperature and high humidity exceeding 30 degreeC, such as a summer night.

As shown in Tables 3 and 4, in the dry cellulose gel in the case of kneading in the air, it can be seen that both the absorption ratio and the swelling are also inferior to those of the dry cellulose gel of the present invention.

Claims (7)

15-25 wt% of cellulose powder is added to the kneading vessel containing water while spraying misty water, followed by kneading water and cellulose powder under vacuum to obtain a cellulose kneaded product, and to the cellulose kneaded product. The manufacturing method of the dried cellulose gel containing the process of irradiating an electron beam and obtaining a crosslinked cellulose gel, and the process of drying the said crosslinked cellulose gel and obtaining a dry cellulose gel. The method of claim 1,
The irradiation amount of the said electron beam is 9-16 kGy, The manufacturing method. 3. The method according to claim 1 or 2,
The said drying is a manufacturing method performed at the temperature of 60-90 degreeC. The method according to any one of claims 1 to 3,
The manufacturing method further includes the process of shape | molding the said cellulose kneaded material under vacuum. The dry cellulose gel obtained by the manufacturing method in any one of Claims 1-4 whose absorption magnification calculated | required by dividing the gel which absorbed for 24 hours by the initial weight before absorption is 150 or more. As an apparatus for implementing the manufacturing method of the dry cellulose gel in any one of Claims 1-4,
A vacuum kneading apparatus including a kneading kiln, a stirring blade, a raw material inlet, a water pipe formed along an inner circumferential portion above the raw material inlet, and a water spraying unit formed at equal intervals in the water pipe, and a vacuum suction unit;
An electron beam irradiation device including a belt conveyor for conveying the cellulose kneaded product prepared in the vacuum kneading apparatus, an electron beam irradiation unit, and an electron beam source; And
The manufacturing apparatus of the dry cellulose gel provided with the air permeable belt conveyor which conveys the cellulose gel prepared by the said electron beam irradiation apparatus, the circulation fan which blows hot air from above the said belt conveyor, and the drying apparatus provided with an exhaust duct. The method according to claim 6,
The apparatus further equipped with the extrusion apparatus which knead | mixes the cellulose gel carried out from the said electron beam irradiation apparatus, and shape | molds in spherical form.

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